Power interrupter for electrical appliances



Dec. 2l, 1954 J. x.. LITTLE 2,697,765

POWER INTERRUPTER FOR ELECTRICAL APPLIANCES Filed May 18, 195] 53 .MMM

ATTORNEYS television receivers.

period of time. 4varied at the will of the user.

United States Patent O POW'ER INTERRUPTER FOR ELECTRICAL APPLIANCES John L. Little, Falls Church, Va.

Application May 18, 1951, Serial No. 227,063

Claims. (Cl. 20o-122) The present invention relates to a device for temporarily interrupting the supply of power to an electrical appliance such as a radio or television receiver. The de vice includes means for automatically restoring the power to the appliance after elapse of a pre-selected interval of time.

AOne of the principal fields of utility for the device of the present invention is in connection with radio and Many persons regard as objectionable the advertising known as commercials which form a part of most radio programs. There has long been a demand for a simple and inexpensive device which would permit a Aradio listener or television viewer to eliminate the advertising or commercial portions of programs. This device accomplishes that objective by permitting the listener or viewer to interrupt manually the power supply to the receiving apparatus. The interruption .of power thus eliminates the portion of the program immediately following the manual interruption. The device is eliective for automatically restoring power after a pre-selected This pre-selected period of time may be The primary object of my invention is to provide a simple and inexpensive device which enables the electrical power to electrical appliances such as radio and television receivers to be manually interrupted and Vto be automatically restored after elapse of a pre-selected period of time.

Another object of the invention is to provide a device of the type described which has .provision for manually restoring the power supply to the appliance before the expiration of the preselected period of time, if that seems desirable. Still another object of the invention is to provide a device for the purpose described which requires no alteration of the appliance and which can be installed by anyone having the slightest knowledge of electrical appliances.

The foregoing and other objects and advantages of the invention will be understood from the following detailed description which has reference to the accompanying drawings, wherein: e

Figure 1 is a longitudinal sectional View of a device embodying my invention, showing the elements of the device in closed-circuit position;

Figure 2 is a view similar to Figure l, but illustrating the elements of the device in position to interrupt the source of power to the appliance; and,

Figure 3 is a fragmentary sectional view of the thermally responsive latch portion of the device.

The device includes a connecting adapter 4 having prongs 5 which can be inserted into any conventional wall or iioor socket. The adapter 4 also has cavities 6 for reception of the prongs 7 of the conventional plug 8 which may be connected to the radio or television receiver or other appliance by means of the wiring 9. The electrical connection from one of the prongs 5 to the corresponding cavity 6 is through the power-interrupting device through the wiring 10.

The power-interrupting device is provided with a housing 11 which may be of any suitable material. One wire 12 of the wiring 10 is connected to a stationary bracket 13. A resilient spring member 14 has one end secured to the bracket 13 by means of a screw 15. The spring member 14 carries a movable contact 16 positioned to cooperate with a stationary contact 17, which is lixed to a stationary bracket 18. A wire 19 is secured to the stationary bracket 18 by means of a screw 20, and this wire 19 leads to an on-and-oi switch 21. A wire 22 connected to the switch 21 forms the second wire of the wiring 10.

The resilient spring member 14 may be deflected to separate the contacts 16 and 17 by depressing a button 23 carried by a stem 24 which projects through an aperture 25 in the housing 11. A thermally responsive latch assembly is provided and designated generally by the reference numeral 26. This latch assembly includes a lever 27 which is pivotally mounted on the housing ,11 by means of a screw 28. A thermally responsive bimetallic member 29 has one of its ends secured to the lever 27 by means of a screw 30. The bimetallic element 29 vis surrounded by an electrical heating coil 31, provided with suitable insulation 32. The electrical heating coil 31 has one of its ends secured in electrical contact to the bimetallic element at 33. The opposite end of the heating coil is connected to the stationary bracket 18 by means of the screw 2t). A wire 34 extends from the screw 15 on the stationary bracket 13 to make electrical contact with the lever 27 at the screw 28.

The resistance of the heating coil 31 is relatively high, and very little current will ow through that coil while the contacts 16 and 17 are closed and power is being supplied to the appliance. However, by depressing the button 23, the contacts 16 and 17 are separated and it will be apparent that current will then flow through the heating coil 31, although such current will be insufiicient to operate the appliance because of the high resistance of the heating coil 31. Figure 2 illustrates the device just subsequent to manual operation to interrupt the power supply. As shown in that figure, the bimetallic element 29 occupies a position to prevent the spring member 14 from closing the contacts 16 and 17. Current has started to ilow through the heating coil 31. After elapse of suilicient time to heat the bimetallic element 29, that element will have its lower end detlected to the left to such an extent that the spring member 14 will be released, enabling it to close the contacts 16 and 17. The power is thus automatically restored to the appliance.

The period of time which will elapse between manual interruption and automatic restoration of the power will depend on several factors. One important `factor is the position occupied by the lower end of the bimetallic element 29 when that element is cold or at ambient temperature. That position can be adjusted by raising or lowering the free end of the lever 27. This can be accomplished by means of a threaded screw 35 provided with an abutment member 36 and a knurled knob 37. The screw 35 is provided with a compression spring member 38 which urges the abutment member 36 against the interior of the housing 11. It will be seen that the free end of the lever 27 and consequently the free end of the bimetallic element 29 may have their positions adjusted by rotation of the knob 37. In this way the period of time between manual interruption and automatic restoration of power can be adjusted.

The lower end 39 of the bimetallic element 29 is curved in the direction of the spring member 14. This insures that the free end of the spring member 14 will be suddenly and fully released at the instant the bimetallic element 29 is deflected by the required amount. Frictional or sliding movement between the free end of the bimetallic element and the free end of the spring member 14 is thus minimized.

The device may be used in the following manner. The Wiring 10 is preferably of suflicient length to reach from the wall or floor outlet to the chair occupied by the user. When the user hears or sees the beginning of a commercial or other portion of a program which he nds objectionable, he can depress the button 23, thereby interrupting the source of power to the radio or television receiver. The knob 37 is preferably so adjusted that the power will not be restored to the appliance for the period of time which experience indicates to be the normal duration of the objectionable portion of the program. The power will be automatically restored after elapse of that period of time. The power can be manually restored prior to expiration of the pre-selected time by manually depressing the knob 37 against the action of the spring 38. Depression of the knob 37 causes the lower end of the rice bime'tallic element 29 to release the spring member 14. The on-and-ot switch 21 may be used to interrupt manually the source of power for longer periods of time.

In some instances it may be desirable to use the device to interrupt the power to some component part of the radio or television receiver as distinguished from interrupting the primary power input circuit.

I have illustrated and described what I now consider to be the preferred form of my invention. However, it will be understood that this form of the invention is exemplary only, and that various modifications may be resorted to without departing from the broader scope of the invention as defined by the following claims.

What I claim is:

1. A power interrupter for electrical appliances comprising a first circuit the impedance of which is of a magnitude to prevent flow of operating current therethrough to the appliance, a heating resistor in said first circuit, a second circuit of low impedance shunting said irst circuit, a pair of relatively movable contacts in said second circuit for opening and closing the same, a spring member urging said contacts into closed position, manually operated means for opening said contacts against the action of said spring member, a thermally responsive latch having an ambient temperature position in which it engages said spring member to maintain said contacts open and having an elevated temperature position in which it releases said spring member for closing of said contacts, said latch being in juxtaposition to said heating resistor to be heated by said resistor upon ow of current through the resistor while said second circuit is open.

2. Apparatus as dened by claim 1, which includes means for manually disengaging said latch from said springi member to permit said contacts to be prematurely c ose 3. A manually actuated electrical power interrupter for radio and television receivers which is capable of automatic restoration of power after elapse of an interval of time, comprising a rst circuit the impedance of which is of a magnitude to prevent ow of suicient current therethrough to operate the receiver, a heating resistor in said first circuit, a second circuit of low impedance shunting said rst circuit, a pair of relatively movable contacts in said second circuit for opening and closing the same, a spring member urging said contacts into closed position, manually operated means for deecting said spring member to open said contacts, a thermally responsive latch having an ambient temperature position in which it engages the deected spring member to maintain said contacts open and having an elevated temperature position in which it disengages said spring member to close said contacts, said latch being in juxtaposition to said heating resistor and being arranged to be heated by said resistor during ow of current through the resistor while said second circuit is open.

4. Apparatus as deiined by claim 3, which includes means for adjusting said latch to thereby adjust the elevated temperature at which said latch disengages said spring member and to thus adjust the length of the time interval that power to said appliance is interrupted.

5. A power interrupter for electrical appliances comprising a first circuit the impedance of which is of a magnitude to cause the ow of current therethrough to be substantially below the operating current of an appliance to be controlled, a heating resistor in said rst circuit, a second circuit of relatively low impedance in parallel relation to said irst circuit, a pair of relatively movable contacts for opening and closing said second circuit, means biasing said contacts toward closed position, manually operated means for opening said contacts against the action of said biasing means, and a thermally responsive latch having an ambient temperature position in which it engages said biasing means to maintain said contacts open and hav ing an elevated temperature position upon being heated by said resistor in which it releases said biasing means for closing said contacts, said latch being in juxtaposition to said resistor to be heated by said resistor upon flow of current through the resistor while said second circuit is open.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 1,485,580 Zimmerman Mar. 4, 1924 1,546,605 Norden July 2l, 1925 1,698,548 Kaufman Jan. 8, 1929 1,948,938 Lawton Feb. 27, 1934 2,043,470 Dyer et al. June 9, 1936 2,147,754 Rivers Feb. 2l, 1939 2,200,309 Siedle May 14, 1940 

